Measure optical power on multimode and single-mode fiber with a FiberMASTER instrument intended for fiber-link test work. Omni Cable ST-R240PMIV identifies the MM/SM power-meter configuration. Its function is to provide optical-power readings when technicians need to evaluate a fiber path rather than install passive cabling or termination hardware. In a real fiber deployment, a power meter belongs at the test stage. Technicians use optical-power measurement to assess link conditions during installation, fault isolation, and scheduled maintenance. Coverage for both major fiber modes lets one instrument address mixed optical environments containing multimode runs as well as single-mode runs. This makes the meter relevant wherever a technician must work across more than one fiber type. This specific FiberMASTER configuration is designated for MM/SM operation, making fiber-mode coverage its defining product characteristic. It is a test instrument, not a cable, transceiver, adapter, or passive fiber component. Match the meter's required test setup to the fiber plant and measurement procedure used at the site, particularly when validating a link or investigating an optical-power issue.